As it is known by persons those skilled in the art, the pressurized containers used in the state of the art for LPG bottles for domestic and industrial use, oxygen cylinders, gas cylinders employed in soldering processes and other pressurized vessels and/or containers, are integrally made from a metallic material.
Typically, said pressurized containers or bottles are manufactured from two end sections formed from metallic (generally steel) plates, rounded up in plate rolls or stamped in large capacity presses to a generally tubular or similar format, having a closed end and an open end, which sections are soldered to each other along the edges of their open ends to form a closed body or housing.
A first ring-shaped element is soldered to the upper half of said pressurized containers to provide a handle portion and a second ring-shaped element is soldered to the bottom half of the container to define a support or base portion of the container.
Additionally, said pressurized containers are also provided with a seat portion centrally positioned in its upper half, said seat portion having an inner thread for receiving the outer thread of a valve element that connects and controls the flow of gas between the container and a device where said gas is used, said seat portion also being mounted to the body of said container by soldering.
A problem of the pressurized containers known in the state of the art are the damages they withstand from shocks and impacts they suffer while being handled for loading and unloading from trucks, stacking for storage and/or during the procedure of being reloaded or refueled with gas. In other words, in a number of situation while being used these pressurized containers may suffer impacts which can reduce its lifetime and/or increase the maintenance cost.
This condition is particularly aggravated when the upper or handle ring and/or the lower or support/base ring elements, mainly the latter, which suffers more impacts when of the loading and unloading of the container for transportation and stacking for storage, need to be replaced.
More specifically, the replacement of the upper or handle ring and/or of the lower or support/base ring elements demands their wearing and tearing as well as the rupture of the soldering points through which they are mounted to the container, the priming of the points of the surface of the container where said upper or handle and lower or support/base ring elements were mounted and, following that, the soldering of new upper or handle ring and/or of the lower or support/base ring elements.
Each one of the above steps means submitting the material of the pressurized container to successive heating and cooling cycles, which with time compromise the integrity of the metallic structure of the pressurized container.
The replacement of the upper or handle ring and the lower or support/base ring elements, in addition from being extremely labor intensive, reduces the useful lifetime of the containers due to the heating and cooling cycles to which they are submitted. Furthermore, the cost of repairing the containers is substantially high and, accordingly, the cost-benefit ratio of the operation is not profitable.
In addition to the above, the frequent replacement of the upper or handle ring and/or of the lower or support/base ring elements means a significant increase of the total costs involved in the maintenance of the pressurized containers used by the industries that commercialize LPG and other pressurized gases, a factor that limits the profit of these business due to the fact that often these costs cannot be passed on to the consumers because generally speaking LPG and other gases normally have their prices controlled by the government.
In addition to the above-mentioned problems and disadvantages, as said upper or handle ring and/or said lower or support/base ring elements, as well as the structure of the pressurized containers are manufactured from steel, this fact implicates in that said rings and containers being frequently painted, a finishing touch which is not entirely efficient with regards to resistance to damage and/or wear and tear.
From the above, it is easy for a person skilled in the art to realize that said upper or handle ring and/or said lower or support/base ring elements are subjected to wear and tear which increases the risk of corrosion, particularly when the layer of paint that covers them is damaged.